Dennis,

I'm not certain it's the case, but I thought I heard someplace that the shear friction between the inboard and outboard wing section spars due to clamp-up force (driven by wing bolt torques) contributes an important amount to total strength.  If anyone who knows for sure, please correct me if I'm wrong.

The torque is 40 ft-lbs, as indicated in Rev 4/09-30-6 to page 5-2 of the construction manual (upper left in green).  Based on a rough calculation, I estimate this amounts to about 10,000 lbs of bolt tension (clamp-up force for each bolt).

 Cheers,
- Kyrilian


Dennis Johnson <pinetownd@volcano.net> wrote:

>Does anyone know the torque specs for the two wing spar bolts on the Legacy? 

 

 

I asked my aero engineer friend the same question when I was building my Legacy.  He said that one purpose of torquing a fastener is to make sure that the torque exceeds the tension load experienced by the fastener while it's in use.  I think what he meant is that you want the tension on the bolt to be high enough that it's not possible for any "play" to develop from further stretching the bolt when the bolt is in use.

 

The Legacy's wing bolts are mainly stressed in shear and are under light tension load, so the "correct" torque is probably not critical.  I looked up the standard torque of that size bolt, which was way more than I could achieve in such a cramped space. 

 

Best,

Dennis Johnson

Legacy, 110 hours   

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